It breaks into flat-sided blocks. Usually it burns with a bright-yellow,
smoky flame. In a good stove or furnace a soft-coal fire should not
give off unpleasant odors and should not "smoke up" the curtains or
walls. If it does either of these things, the fire is not getting
enough air, and coal is being wasted (because it is not being completely
Hard coal, or anthracite-- at least, the best of it-- is shiny and rather clean. It breaks into pieces with sides a little curved. It burns with pretty flames, short and blue, not very bright, and almost smokeless and odorless. Housewives like anthracite, for it is easy to keep a house clean where hard coal is burned.
You may have an open fireplace in which big chunks of cannel coal are burned. Cannel coal is dull black, and almost as clean to handle as hard coal. It burns with a very hot, bright-yellow flame. You can light some cannel coal with a match, as you would a candle. In fact, the name "cannel" came from "candle." "Cannel coal" is really "candle coal".
Brown coal, or lignite, is usually brown but sometimes almost black. It has a woody grain. The name "lignite" comes from a word meaning "wood." Much lignite is soft and moist when fresh, and cracks to pieces or crumbles to powder when dry. Brown coal gives out less heat in burning than the black coals do.